Methods for improving uplink (UL) coverage, throughput, and transmission latency are currently being investigated in the third generation partnership project (3GPP). In order to achieve these goals, enhanced uplink (EU) transmissions have been proposed in 3GPP, in which control, (i.e., scheduling and assigning), of UL resources, (i.e., physical channels), is moved from a radio network controller (RNC) to a Node-B.
FIG. 1A shows a conventional wireless transmit/receive unit (WTRU), (e.g., mobile station), side medium access control (MAC) architecture 100. The WTRU MAC architecture 100 includes a MAC-es/MAC-e entity 105, which comprises different independent sub-layer entities within the MAC. The MAC-es/-e functionality split is a result of how the MAC functionality is partitioned within the universal terrestrial radio access network (UTRAN). The WTRU MAC architecture 100 further includes a high speed MAC entity 110, a MAC-c/sh 115, a dedicated channel MAC (MAC-d) 120 and a MAC control service access point (SAP) 125. The MAC-c/sh 115 controls access to all common transport channels, except the HS-DSCH transport channel 145. The MAC-d 120 controls access to all dedicated transport channels, to the MAC-c/sh 115 and the MAC-hs 110. The MAC-hs 110 controls access to the HS-DSCH transport channel 145.
The MAC-es/MAC-e entity 105 controls access to an E-DCH 130, whereby the MAC-d 120 may access the E-DCH 130 via a connection 135, and the MAC control SAP 125 may access the E-DCH 130 via a connection 140.
FIG. 1B shows MAC interworking in the conventional WTRU of FIG. 1A. As shown in FIG. 1B, a radio link control (RLC) protocol data unit (PDU) enters the MAC-d on a logical channel. In the MAC-e header, a data description indicator (DDI) field, (6 bits), identifies the logical channel, MAC-d flow and MAC-d PDU size. A mapping table is signaled over radio resource control (RRC) signaling to allow the WTRU to set the DDI values. The N field, (fixed size of 6 bits), indicates the number of consecutive MAC-d PDUs corresponding to the same DDI value. A special value of the DDI field indicates that no more data is contained in the remaining part of the MAC-e PDU. The transmission sequence number (TSN) field (6 bits) provides the transmission sequence number on the E-DCH 130 shown in FIG. 1A. The MAC-e PDU is forwarded to a hybrid-automatic repeat request (H-ARQ) entity, which then forwards the MAC-e PDU to layer 1 for transmission in one transmission time interval (TTI).
An efficient MAC architecture for scheduling the transmission of E-DCH data is desired.